I would vote for the F350 with 4.30 gears. Fuel mileage won't be that different. As a former V10 owner and now a diesel owner, I will say this. My next truck will probably be gas. My V10 was just as capable as this 7.3 diesel I now drive. It just does it differently. To the OPer. Either the F250 or the F350 will do the job. There won't be a big difference in the fuel mileage especially towing. The 4.30 rear will make towing much easier. Go to the Ford Truck Enthusiast forum for the 6.2 and read to your hearts content. Good luck, John